Method of drying lumber



Patented May 6, 1930 UNITED STATES PATENT FFICE J PEARL WILSON, OF JACKSONVILLE, FLORIDA, ASSIGNOR TO WILSON-OTWELL 8r.

CONE, INCL, OF JACKSONVILLE, FLORIDA, A CORPORATION OF FLORIDA METHOD OF DRYING LUMBER No Drawing.

This invention relates to an improvement in a method of drying lumber.

The object of the invention is to dry lumber thoroughly to the center before the pores of the lumber have had an opportunity to close,

and before shutting in the moisture and making it necessary to use suflicient heat or drying medium to open these pores before it is possible to withdraw the moisture. It has 10 been found in practice that a large amount of heat is wasted in this way. It can be saved if the drying operation takes place be fore the pores of the lumber have closed.

When the lumber is sawed, the pores are is open, and in the case of small lumber it may be run directly into the dry kiln where the drying may take place. It is however undesirable to mix the large and small lumber together, because the latter dries very much quicker than the former, and there should be a separation in order that the small lumber may be removed from the kiln when it is thoroughly dried, while allowing the large size to remain therein a sufiicient length of time required to remove the moisture content. 1

In sawing a log. it is cut into several dilfen ent pieces of varying sizes in order to obtain the greatest possible amountof lumber while decreasing the amount of waste. In order to do this, there will only be a small number of pieces of large size with a greater number of small size. The latter accumulate a great deal faster than the former, and since these should not be placed on the same truck for the drying operation but instead should be separated, it will take considerable timevery often in which to accumulate a truck-load of the large size. In order that it will not have to remain in the open air during this time,

which would tend to close its pores, it is preferable that this lumber should be immersed in hot water to keep the pores open and'to heat it entirely to the center. Y 7 Therefore this invention involves the taking of the lumber directly from the saw and as soon as possible after the sawing operation, before the pores have had an opportunity to close, stacking it on a cradle with the usual sticks between the lumber and lowering this Application filed October 6, 1927. SerialNo; 224,528.

cradle into a tank of hot water which, however, is not sufiiciently hot, as to, cause a scalding of a workman, and then raising the temperature of the water approximately to boiling point, namely 212 degrees F.,inorder 5 to heat the lumber to its center and to prevent the closing of its pores. l Vhenever the lumber is thus heated throughout, it may be withdrawn from the tank of hot water and loaded on a truck and run directly into the to dry kiln where it will dry along with the small sized lumber and in approximately the same length of time. Q

Thevcradle may be lowered into the tank by means of a hoist or other suitable arrangement. The heating of the water may be by means of steam or steam coils arranged in the tank suflicient for this purpose. The large sized lumber is placed on a cradle prefer: ably as soon as it is taken from the sawf'iu but at any rate before the pores have had an opportunity to close, and it is immediately lowered into the tank of hot water, and after a full charge has accumulated on this cradle the temperature of the water is raised to boil- 7'5 ing point, as mentioned above. This heats the lumber throughout and entirely to the center without exposure to the air, after which it is ready to be placed in an ordinary dry kiln, which should be done without delay, so

' where the heat of the kiln and the heat of the lumber cause a drying'of the lumber from the center outwardly, instead of from the outside inwardly, and allows the pores to conn tract and the shrinkage to take place in an ss even, normal manner without injury to the lumber.

This method of drying is especially applicable to red gum, southern oak, and other kinds containing a larg percentage of mois--= ture content, because it allows for an even removing of the moisture without case-hardening and preventing inside honeycombing. The time required for the lumber to remain in its hot bath depends upon the kind andsa thickness of the lumber.

In this way a new method of drying lumber has been devised which has proven very successful, and it is a radical departure from the usual method of drying lumber, accomplishing a more thorough drying operation in a very much shorter length of time than Where the lumber is allowed to stand in the air until after its pores are closed.

Reference in the claims to the closing of the pores of the lumber is intended to designate either a contraction of the cellular structure and, or, a sealing of the pores due to the resins, sap, etc., contained in the wood, which becomes oxidized to form a seal.

I claim 1. A method of drying lumber including immersing the lumber in a hot bath before the pores have become closed.

2. A method of drying lumber including immersing the lumber in a hot water bath before the pores have had an opportunity to become closed.

3. A method of drying lumber including immersing the lumber in a hot water bath immediately after sawing and before the pores have had an opportunity to close, and thereafter subjecting the lumber to artificial drying.

4. A method of dry lumber including passing the lumber directly from the sawing operation into a hot water bath before the pores have had an opportunity to become closed, raising the temperature of the hot water bath to approximately boiling point for heating the lumber to the center and thereafter directly subjecting the lumber to artificial drying for completing the drying operation.

5. A method of drying lumber including passing the lumber directly from the sawing operation into a hot water bath before the pores of the lumber have become closed, raising the temperature of the hot water bath approximately to boiling point, allowing the lumber to remain in said hot water bath until heated approximately to its center and thereafter removing the lumber and subjecting the lumber to artificial drying for completing the drying operation and allowing an even and thorough drying of the lumber.

In testimony whereof I aflix my signature.

J PEARL WILSON. 

